The primary goal of the proposed research is the study of language comprehension from a cognitive neuroscience perspective. The experiments outlined in the current proposal are focused on providing answers to questions about the sequence and timing of neural events that underlie the perceptual and cognitive processes involved in visual word comprehension. The proposed approach entails the recording of event-related brain potentials (ERPs) while subjects perform tasks designed to tap specific aspects of visual word processing. The proposed research has three specific aims. The first is to test and elaborate on predictions of the Bi-modal Interactive Activation Model (BIAM) of word comprehension in competent adult users of language. While models like the BIAM have been touted as neurally plausible, relatively little work using cognitive neuroscience methods has actually attempted to test the predictions of such models. The second complementary aim focuses on improving the precision of ERP measures of word processing by providing a better understanding of their relationship with the perceptual, cognitive and linguistic processes they are hypothesized to reflect. The third aim seeks to improve our understanding of word comprehension by examining how comprehension processes develop over time. The 25 experiments that are proposed to achieve these aims are organized into three groups of studies. The first group, which includes 18 masked priming experiments to be conducted in young adults, uses our short interval repetition priming paradigm. In pilot work this paradigm has allowed us to isolate four temporally overlapping ERP effects that we have hypothesized are sensitive to a cascade of word comprehension processes. The experiments outlined in this section of the proposal will test predictions about the processing nature and timing of these ERP effects and use these ERP effects to test predictions generated by the BIAM. The second group includes four single word experiments, also in young adults, where a number of variables will be manipulated that have previously been suggested to influence early visual word comprehension processes. We hypothesize that previous failures to see effects with these variables were due to lack of power. We will increase the power of our designs and determine if effects early in the time-course of word processing can be obtained. The final group of studies will include three word comprehension experiments modeled on those proposed in the young adult subjects but run in five groups of children between 7 and 11 years of age. These experiments will allow us to examine the development of visual word comprehension over time and thus better characterize changes in some of the neural/cognitive processes involved in reading. One long term goal is to extend these studies to children and adults with word processing and other language/cognitive deficits.